So theoretically you could hit it on T-Mobiles 1900 band, if the stars align.

So, I'm still confused here -- will I be able to get HSPA+ speeds on my iPhone 4S if I'm in a major metro area and listed under T-Mobile's refarmed networks? I'm not asking about AT&T, and I'm not asking about Nexus, just iPhone 4S and T-Mobile

So, I'm still confused here -- will I be able to get HSPA+ speeds on my iPhone 4S if I'm in a major metro area and listed under T-Mobile's refarmed networks? I'm not asking about AT&T, and I'm not asking about Nexus, just iPhone 4S and T-Mobile

Yes. Your HSPA+ coverage may be spotty though. If you don't get an HSPA+ signal you will fall back to EDGE coverage.